1. Field of the Invention
The invention generally relates to the field of reprocessing medical equipment. In particular it relates to an improved device and method for sterilizing and reprocessing endoscopes and will be described with particular reference thereto. The invention also relates to an improved device for sterilizing and reprocessing endoscopes in combination with a novel fast acting room temperature sterilant and methods of using the same.
2. Description of the Related Art
Sterilization connotes the absence of all life forms, including bacterial endospores which are the living organisms most resistant to conventional sterilants. Disinfection, by distinction, only connotes the absence of pathogenic life forms. Microbial decontamination is generic to both sterilization and disinfection.
Medical equipment is often sterilized at high temperatures. Commonly, the equipment is sterilized in a steam autoclave under a combination of high temperature and pressure. While such sterilization methods are very effective for more durable medical instruments, more sensitive medical instruments formed of rubber and plastic components with adhesives are wholly unsuited to the high temperatures and pressures associated with a steam autoclave. In particular, highly complex instruments which are often formed and assembled with very precise dimensions, close assembly tolerances, and sensitive optical components, such as endoscopes, may be destroyed or have their useful lives severely curtailed by harsh sterilization methods employing high temperatures and pressures. Further, endoscopes present particular problems in that such devices typically have numerous exterior crevices and interior lumens which can harbor microbes and thus be difficult to clean and sterilize using ordinary techniques. Therefore, the employment of a fast acting, low corrosivity sterilant is more desirable for reprocessing sensitive instruments, such as endoscopes.
Early efforts to sterilize more sensitive medical instruments, such as endoscopes, have met with limited success and all conventional methods have associated problems or detractions. Sensitive medical instruments, such as endoscopes, are often sterilized with ethylene oxide, which is thermally less severe than steam. The endoscope must be exposed to the ethylene oxide for a relatively long period, on the order of three and a half hours. Thereafter, eight to twelve hours are normally required for de-gassing or desorbing the ethylene oxide from plastic and other materials which are capable of absorbing the ethylene oxide. The pressurization and depressurization cycles of ethylene oxide sterilization may damage lens systems and other delicate instruments which are commonly integral with endoscopes. Moreover, the ethylene oxide is relatively expensive. It is sufficiently toxic and volatile that extensive precautions are commonly taken to assure operator safety. Therefore, the employment of a fast acting, low corrosivity sterilant which is nontoxic and preferably biodegradable for easy disposal would be more desirable for reprocessing sensitive instruments, such as endoscopes. Other medical or dental instruments which have lumens, are also in need of a method of cleaning and sterilizing which employs an effective device and sterilant which will not harm sensitive components and materials. Further, the need exists for a reprocessing system having a shorter reprocessing time cycle.
Liquid systems are commonly used for disinfecting endoscopes and other heat sensitive and delicate instruments. Using liquid sterilants or disinfectants to achieve disinfection is normally rapid, cost-effective and does minimal damage to the medical devices. Commonly, a technician mixes a sterilant composition and manually immerses the item to be disinfected. The immersion is timed by the technician. Technician variation in the mixing, timing, and equipment handling raises problems of assurance and reproducibility of the manual disinfection process. Rinsing of the items to remove chemical residues also adds a variable that reduces the assurance of disinfection or sterility. Once, rinsed, the disinfected endoscope or other item is susceptible to recontamination by airborne microbes. Conventional liquid systems require complete immersion of the endoscope in the liquid solution. Large and bulky items such as endoscopes require large immersion containers and equally large volumes of expensive sterilant or disinfecting solution. Further, merely soaking endoscopes in a sterilant or disinfectant is unacceptable since numerous pockets exist within the tubing that the sterilant or detergent cannot reach effectively. This leaves areas of contamination within the endoscope. With the prevalence of highly contagious diseases such as Hepatitis B and Acquired Immune Deficiency Syndrome, effective sterilization, or disposal, of all medical tools becomes mandatory. Accordingly, an ineffective effort to sterilize endoscopes by merely soaking is unacceptable. For example, U.S. Pat. No. 5,091,343 discloses a liquid sterilization system which involves placing the instrument to be sterilized in a tray or cassette which is then covered and positioned within a liquid sterilization unit. Within the unit the cassette or tray is filled with liquid sterilant, rinsed with a sterile rinse water and the rinse water drained away. As the rinse water is drained away, sterile air is introduced into the cassette or tray. The cassette or tray is removed from the unit and the process is completed with uncovering the instrument and removing it for storage or use. A major drawback of this type of process is the lack of assurance of a sufficient flow of sterilant and rinse water through the interior passages of the instrument. The low pressure circulation of the liquid sterilant in the cassette or tray and the numerous pockets inherent in such a tubular instrument provides no assurance that adequate sterilization is attained in the interior passages of the instrument. The exterior surfaces of instruments, such as endoscopes, typically have multiple connectors and branches which can define small crevices or niches harboring microbes. Because of this, low pressure circulation liquid sterilization systems, which rely on complete submersion of the endoscope, may also be inadequate to assure complete sterilization of all exterior surfaces.
Further, conventional systems for sterilization of endoscopes are designed to operate on a solitary cycle; that is, once the sterilization process has been initiated, it must be completed before a second instrument can be reprocessed and sterilized. This limitation results in unnecessary delays and severely restricts the capacity of a system for reprocessing instruments.
A need therefore exists to provide a device which can be used in combination with a fast acting, low corrosivity sterilant to effectively reprocess and sterilize complex medical instruments with lumens, in particular, such as endoscopes.